I've never heard that story anywhere else (not that I'm saying its untrue), it seems strange Hagler would want Leonard as a drinking partner even before they fought.
I've read that they met up for an opening of a restaurant Ray invited Marvin and it was there Hagler mentioned getting old etc.
According to SRL Tommy ask him to do some exhibitions with him. SRL said; "Look at me Tommy. I can't get hit no more by nobody." SRL said that during the build up to Contender Season I.
Sounds a bit more believable, tho i'd hardly say Hagler talking getting old had Ray tying him up and having him delivered to the ring Cheers